package study.nzy.com.studydemo.utils;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {

    static final String DATABASE_NAME="MyDatabase.db";

    static final String TAB_NAME="users";

    public static final String FIELD_NAME="name";
    public static final String FIELD_PASSWORD="password";
    public static final String FIELD_AGE="age";

    SQLiteDatabase db;

    public DBHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);  // 参数为数据库名称，版本号
        db = getWritableDatabase();
    }

    @Override
    public void  onCreate(SQLiteDatabase sqLiteDatabase){
        String createTableSQL = "CREATE TABLE "+TAB_NAME+" (" +
                "id INTEGER PRIMARY KEY AUTOINCREMENT,"
                +FIELD_NAME+" TEXT,"
                +FIELD_PASSWORD+" TEXT,"
                +FIELD_AGE+" INTEGER)";
        sqLiteDatabase.execSQL(createTableSQL);
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }

    public long addUser(ContentValues values){
        return db.insert(TAB_NAME,null,values);
    }

    public int updateByName(String name, ContentValues values){
        return db.update(TAB_NAME,values,FIELD_NAME+" =?",new String[]{name});
    }

    public int delete(String name){
        return db.delete(TAB_NAME,FIELD_NAME+" =?",new String[]{name});
    }

    public String findPasswordByName(String name){
        String pwd = null;
        String selection = FIELD_NAME+" =?";
        Cursor cursor = db.query(TAB_NAME, null, selection, new String[]{name}, null, null, null);
        if (cursor!=null && cursor.moveToFirst()){
            pwd = cursor.getString(2);
            cursor.close();
        }
        return pwd;
    }

    public void closeDB(){

        if (db!=null && db.isOpen()){
             db.close();
        }
    }
}
